A USER-CENTERED ENGINEERING APPROACH TO STORAGE AND ACCESS IN

HIGH PRIORITY SCENARIOS

by

Varun Ananthasivan Srikrishnan

A thesis submitted to the graduate faculty

in partial fulfillment of the requirements for the degree of

MASTER OF SCIENCE

Major: Industrial Engineering

Program of Study Committee:

Dr Richard Stone, Major Professor

Dr Leifur Leifsson

Dr Gary Mirka

The student author, whose presentation of the scholarship herein was approved by the program

of study committee, is solely responsible for the content of this thesis. The Graduate College will

ensure this thesis is globally accessible and will not permit alterations after a degree is conferred.

Iowa State University

Ames, Iowa

2019

Copyright © Varun Ananthasivan Srikrishnan, 2019. All rights reserved.

ii

TABLE OF CONTENTS

Page

LIST OF FIGURES ....................................................................................................................... iii

LIST OF TABLES ......................................................................................................................... iv

ACKNOWLEDGMENTS ...............................................................................................................v

ABSTRACT ................................................................................................................................... vi

CHAPTER 1. GENERAL INTRODUCTION ............................................................................. vii

CHAPTER 2. A USER-CENTERED ENGINEERING APPROACH TO STORAGE AND

ACCESS IN HIGH PRIORITY SCENARIOS................................................................................x

Abstract ...................................................................................................................................... x Introduction and Background .................................................................................................. 11

Theory ...................................................................................................................................... 13 Methodology ............................................................................................................................ 15

Procedure ............................................................................................................................ 15

Participants ......................................................................................................................... 16 Independent variable .......................................................................................................... 16

Dependent variables ........................................................................................................... 16 User-Centered Heuristics ................................................................................................... 16 Phase 1: Control Phase-Testing Participants on the existing arrangement of the

storage rooms-Testing Scenario ......................................................................................... 17

Phase 2: Improvement Phase-Updating the Storage Rooms .............................................. 18 SIMIO Model ..................................................................................................................... 19 Existing System .................................................................................................................. 21

New System ........................................................................................................................ 22 Phase 3: Experimental Phase-Testing Participants on the updated storage rooms ............ 22

Results ..................................................................................................................................... 25 Hypothesis .......................................................................................................................... 25

Quantitative ........................................................................................................................ 25 Qualitative .......................................................................................................................... 28

Discussion ................................................................................................................................ 29 Conclusion ............................................................................................................................... 31

References ............................................................................................................................... 32

CHAPTER 3. General Conclusion ................................................................................................38

APPENDIX A. Informed Consent Form .......................................................................................40

APPENDIX B. Pre-Study Questionnaire .......................................................................................43

APPENDIX C. Post-Study Questionnaire .....................................................................................44

iii

LIST OF FIGURES

Page

Figure 1: Process Involved in the Study ....................................................................................... 15

Figure 2: SIMIO model of the room before user-centered redesign ............................................. 21

Figure 3: SIMIO model of the room after user-centered redesign ................................................ 22

Figure 4: Storage room before user-centered redesign ................................................................. 23

Figure 5: Storage room after user-centered redesign .................................................................... 24

Figure 6: Response collected from post-study questionnaire after the experimental phase ......... 28

iv

LIST OF TABLES

Page

Table 1: Summary of Quantitative Data ....................................................................................... 25

Table 2: Analysis of Variance ....................................................................................................... 26

Table 3: Paired t-test ..................................................................................................................... 27

v

ACKNOWLEDGMENTS

I would like to thank the Director of Graduate Education, IMSE department, Dr. Gary Mirka,

and my major professor Dr. Richard Stone, and my committee member Dr. Leifur Leifsson, for

their guidance and support throughout the course of this research. Additionally, I would like to

thank the Story County Sheriff’s Office for accommodating the experiments conducted and

arranging for sworn officers to participate in the study.

I would also like to thank my friends, colleagues, the department faculty and staff for

making my time at Iowa State University a wonderful experience. I want to also offer my

appreciation to those who were willing to participate in my surveys and observations, without

whom, this thesis would not have been possible.

vi

ABSTRACT

This thesis aims at introducing the importance of the application of user-centered ideologies to the

redesign and organization of storage spaces in high priority/time-critical industries such as law

enforcement and introducing a new area of study that we call “organizational engineering”.

Throughout the thesis, the need for this new user-centered area of study was evaluated by

carrying out experiments on six sworn officers in the miscellaneous equipment storage rooms at

the Story County Sheriff’s Office in Nevada, Iowa. This involved running the officers through a

familiar scenario on the existing system design, redesigning and reorganizing the existing system

using a combination of human-centered heuristics and quantitative data collected to develop an

optimal design using a simulation software; SIMIO, running the officers on the new system and

comparing the data obtained in both cases.

The analysis of both quantitative and qualitative data revealed that the new system was

more intuitive to use and navigate through, easier to learn for new officers and enhanced greater

visibility of the equipment in the room. The data also showed that the newly designed room was

consistent with the design of the previous room and reduced the amount of wasted time by 74%

and the associated cost by 63%. An ANOVA performed on the amount of wasted indicated a p-

value of 0.00038 and a paired t-test of the indicated a one-tailed p-value of 0.01 suggesting the

high possibility of a statistically significant difference between the two times. The data thus

indicated that such user-centered redesigns could greatly reduce the amount of time devoted

towards small duties that could greatly hinder the performance of more important tasks. The results

obtained from this study indicate a potential to use this approach to storage systems in other high-

priority/time-critical industries.

vii

CHAPTER 1. GENERAL INTRODUCTION

User-centered design is an area that has sparked the interest of researchers and companies alike.

The idea of developing machines for use my humans goes back as far as the early 1940’s (Yerkes,

Robert. M, 1941). The late 1940’s and early 1950’s saw applications of human engineering to the

design of human-operated systems (Chapanis et al., 1949; Birmingham et al., 1954). Further, the

aviation sector adopted the human engineering approach in the development of air-navigation and

air-traffic control systems to improve human performance in these scenarios (Fitts, Paul M. et al.,

1951). By the year 1957, about 45 companies had human factors groups with average of ten

personnel per group (Kraft, JA, 1957). This was around the time when human factors began to be

considered important for the safety of people driving cars, owing to the large loss of manpower

associated with vehicle accident injuries (Stapp, John et al., 1957). Although at that time the idea

revolved around developing machines for use by humans, in due course of time, the idea evolved

into the safety of operators of various systems.

As time passed, the concepts of human factors as well as the understanding of the physical

and psychological limits and capabilities of human were used to develop systems that would

require less physical and mental effort to enable the human to perform tasks better (Karat, John,

1997, Albayrak, Esra et al., 2004). A lot of studies began exploring the effects that workplace

elements had on operator task performance (Bosch, T., Mathiassen et al., 2011). Correlations were

drawn between the quality of the process/product produced as a result of human-related limitations

(Drury, C.G, 2000). Around the 1970s, organizations like NIOSH and OSHA were developed with

all this understanding in mind. These organizations had the sole purpose of ensuring worker safety

at companies. Following this, human factors began to be applied towards making products and

systems usable (Bannon, Liam J, 1995).

viii

Literature has shown that workplace organization has been seen to increase productivity in

manufacturing companies (Karwowski, Waldemar et al., 1998). Lean techniques like 5S and

Visual Management have been used to manage various aspects of a production process and ensure

that there is a place for every item. These techniques have been seen to have a strong correlation

to the development of a company’s business (Arvanitis, Spyros, 2005). Additionally, there have

been studies that have shown that investing in human capital and workplace organization has

contributed to the labor productivity in firms across Switzerland and Greece (Arvanitis, Spyros et

al. 2009). Some studies have connected workplace organization to human injuries (Shahnavaz, H.,

1987).

However, in all of the literature in the field of workplace organization and human factors,

there doesn’t seem to be a correlation between workplace organization and human factors. All the

literature in the field of human factors has talked about safety, human-machine issues, human-

centered design of systems and products for use by humans, organizational well-being of workers

etc. While there are correlations between changing certain physical characteristics of a workplace

and human performance. But nowhere does it mention reorganization of workplaces to enhance

human performance, especially, in high-priority work settings. Even though the aviation sector has

employed this idea of reorganization of flight instruments to enhance pilot task performance, such

a concept has not been applied to a work setting like say a storage room. While techniques like 5S

have been employed in storage rooms, there is no correlation between that and human factors. This

thesis aims at establishing this link by not changing any variable but the layout of a workspace.

This paper aims to explain the importance of user-centered redesign of storage spaces in

high-priority and time-critical scenarios by means of a detailed experimental study that was carried

out at the Story County Sheriff’s Office, Nevada, IA. The experimental study involved sworn

ix

officers with duties and responsibilities associated with the miscellaneous equipment storage room

at the Sheriff’s office. The study was comprised of three phases. First, the study was performed on

the existing system and the time taken for each task and the time wasted on looking for items were

recorded. The data obtained from this experiment, the user surveys, user-centered heuristics and a

SIMIO model developed were used to redesign the storage room for the next phases of the study.

The redesign was aimed at creating the most optimal storage room design that would not only

enable the easy accomplishment of the tasks at hand, but also fit within the expectations and

capabilities of the officers. After the redesign, there was a significant drop in the amount of time

wasted looking for equipment in the storage room. The time wasted was translated to a cost

associated with wasting time looking for items in the storage rooms. Both the qualitative and

quantitative data thus obtained indicated that the redesign would not only make the room easier to

navigate, but also would enable the officers to spend more time on actual Sheriff’s office

responsibilities by making the process of locating and retrieving items easier. Moreover, the cost

associated with the wasted time could be used by the Sheriff’s Office to purchase new equipment.

The results indicated a very real need for such user-centered interventions in such time-critical

scenarios to make tasks easier and quicker to perform and to support the capabilities and limitations

of the humans involved in such systems, as has been shown time and again by time-critical

industries like the aviation industry for instance. The data thus obtained indicated the need for

organizational engineering of storage spaces in such environments.

In the upcoming chapter the journal paper associated with this thesis is discussed with the

experiment carried out at the Sheriff’s office along with the results obtained and inferences drawn.

The last chapter concludes the findings inferred from the thesis.

x

CHAPTER 2. A USER-CENTERED ENGINEERING APPROACH TO STORAGE

AND ACCESS IN HIGH PRIORITY SCENARIOS

Modified from a manuscript under review to the Reliability Engineering & System Safety Journal

FNU Varun Ananthasivan Srikrishnan and Dr. Richard T Stone

Abstract

This paper focuses on the organizational engineering of storage spaces to enable easy location and

retrieval of equipment, thus supporting the time-critical nature of operations at a miscellaneous

storage room at the Story County Sheriff’s Office. The idea is to combine the concept of workplace

organization with those of human-centered design to redesign the storage areas to better support

the activities of the officers. In order to implement this idea, experiments were carried out on sworn

officers with duties using a familiar scenario before and after the redesign of the storage room.

After carrying out the first test (before redesign), using user-centered heuristics a SIMIO model

was developed to optimize the redesign of the room to allow for the easiest access and retrieval of

items from the room. The redesign was based on this model as well as participant surveys. As a

result of the complete redesign, a significant reduction in the wasted time was observed as

indicated by a statistical analysis performed. Further qualitative surveys indicated that 83% of the

officers found the new system easier and more convenient to use. The use of labels and pictures to

identify various shelves in the storage room was found to make the system easier to learn and more

intuitive, based on the qualitative surveys. The wasted time calculated was then translated to a cost

and the newly designed storage room was found to have reduced the cost by 63%, money that

could be spent on actions that precluded the efficient accomplishment of tasks. The quantitative

and qualitative results of the study indicate that there is a need for the industry to extend research

towards this field that we name “organization engineering”.

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Introduction and Background

The research interest in of human factors and user-centered design goes back a long way in history.

User-centered considerations began around the time of World War II when countries were

developing airplanes that could go faster and higher than ever before. Designers began to realize

that, in order to be successful in flying these faster aircraft, the pilots’ physique needed to be

considered during the design process. There was a need to design aircrafts according to the human

flying it and to support the capabilities and understanding of the humans flying it. This was one of

the first applications of human factors in high priority and time and safety-critical environments.

The whole idea of fitting the workplace to the human became an important consideration (Wiener,

E. L., & Nagel, D. C. 1988). The early origin and development of the concept of “user-centered

design” began in the years following late 1980s during which time a lot of research was being done

in this area. Some researchers through years of study and experimentation developed principles of

user-centered design that seemed easy to understand and easily applicable to the design of day-to-

day products. (Ben Shniederman, 1987; Norman, 1988; Nielsen, 1993, 2001). These principles

highlighted the importance of intuitiveness in design.

Following this, many researchers and companies alike began exploring the advantages associated

with the incorporating the concepts of human-centered design into the design of products and

systems, thus giving their organizations a competitive edge over others in the market (Ahmad and

Schroeder, 2003; Onyema, 2014). But there was still a lack of knowledge of human-centered

approaches that seemed to have limited the application of human factors to industrial production

(Dul and Neumann, 2009). This lack of understanding drove many laboratory experiments and

tests in different industrial settings that aimed at providing the advantages of incorporating human

12

factors and ergonomic interventions into the design of everyday objects and process improvement.

Many “usability studies” gained popularity during this period. These studies involved changing

certain physical characteristics of the work environments, measuring the effect the change had on

human performance and studying the overall improvement in the process and product quality

(Chaffin, D.B., 2008).

More recently, studies have been done to identify how human-centered approaches can be used in

the manufacturing of products and processes to reduce physical workload on employees. However,

work related to the application of human-centered approaches to the organizational level is greatly

limited. A few studies have incorporated this approach to better relationships between teams, to

improve employee morale, to create a work environment that will favor learning and improve

employee-management relationships (Leonard et al., 2004, Lank, E., 1997). For example, many

companies have incorporated open. One study has touched upon activity-based work environment

and its impact on satisfaction. Most studies have looked at human factors as a means of improving

the quality products and processes, safety of users/operators performing their task or using the

products and to increase their competitive edge over other companies.

Alongside this realization among industries that user-centered approaches were the key towards

attracting customers and keeping them loyal and happy, the defense community began to embrace

ideas of user-centered design for training personnel. For example, the developing virtual

environments that would help train military personnel by providing a visualization of the

battlefield (Hix, D et al., 1999) was an important application that the military was interested in.

Law enforcement agencies were interested in the development of human-centered spatiotemporal

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crime analysis tools (Roth, R et al., 2010, 2013) that could greatly help officers spend more of

their time on law enforcement duties. User-centered design was also used to enhance situational

awareness among officers (Razip, A et al., 2014).

For many decades, the design of exoskeletons (Schnieders, T. et al., 2014) seemed to interest a lot

of researchers and defense communities. From design suits for army personnel to their use as

prosthetics, extensive research has been performed to develop exoskeletons for various purposes.

Most recently, exoskeletons were used in law enforcement for training officers in the use handguns

to ensure accurate, precise, reliable and ergonomically safe postures (Schnieders, T. et al., 2019).

The need for accuracy and precision in a fast-paces and high-priority/security environments of law

enforcement agencies and defense departments seems to make user-centered design very important

in such industries.

Theory

Most of literature talks about applying user-centered techniques to the design of products and

systems that support human capability. Nowhere in the industry or in literature have there been

specific studies that try to link the use of human-centered principles with optimal organization of

workplaces. Similar to aviation where different flight controls and avionics need to be organized

effectively, there is a real need to organize a workspace in a way that allows the user to spend more

time on the task at hand rather than looking for items. This organization can be made based on

functional or natural mapping, user evaluations and non-user evaluations. Even though literature

has shown that human-centric design can improve the quality of a process, it does not tie the

human-centric interventions directly to the performance of the human, there are usually a lot of

variables.

14

This paper describes a Human Factors intervention that was carried out in a Story County Sheriff’s

office storage room with the aim of enhancing the performance of officers, with only one variable;

the changing design of the room alone. In doing so, the hypothesis is that, re-organization of the

workspace will enable the officers to locate and retrieve items quickly and efficiently and will

enable the officers spend less time on the search and more time on their task at hand.

15

Methodology

Procedure

Following is a sequential set of actions that were performed throughout the process:

Get permission from Story County Sheriff’s Office

Taking an inventory of the storage space and get an idea of the location of every item by shelf and row numbers

Develop user-centered heuristics

Running research participants through a familiar scenario using the existing system

Mapping of officers’ responses to post study questionnaire to heuristics

Creating a model of the storage space-SIMIO version 10.174.16986

Reorganization of storage rooms according to the optimal design of the model

Running participants through the familiar scenario for the new setup

Comparing the times taken to retrieve items and time wasted between finds

Figure 1: Process Involved in the Study

16

Participants

Six sworn officers with tasks specific to the miscellaneous equipment storage room participated in

this study. They were selected based on the following criteria:

18 years or older,

Employed by the Story County Sheriff’s Office

Able to legally give consent and

Independent variable

The independent variable in this experiment was the difference in organization between

the existing storage room and that of the new storage room.

Dependent variables

The dependent variable in this experiment was the Time wasted on actions between finds.

The reason for considering “Time Wasted” as a dependent variable was that the wasted time was

identified to be the part of the time taken to perform the task that when extrapolated to other small

tasks that form part of the Story County Sheriff’s Office responsibilities could lead to major loss

of time that could instead have been used by the Story County Sheriff’s Office for more important

duties such as serving the community or processing cases. It was believed that if this time could

be reduced to the minimum, it would greatly benefit the Story County Sheriff’s Office by allowing

the officers to spend more time on important tasks at hand. Additionally, the time wasted was

assigned a cost based on the time wasted by an officer on finding items and the average hourly

salary of deputies at the Story County Sheriff’s Office based on the Des Moines Register (2019).

User-Centered Heuristics

Following were the user-centered heuristics (based on the Nielsen–Shneiderman Heuristics) that

were considered for the redesign of the storage room:

17

Visibility: To ensure that users can see the status of the inventory while retrieving items.

The existing system did not afford the officers with the ability to see whether a particular

type of item was out or not.

Consistency: To ensure that certain elements of the existing system were kept as is to

avoid any confusions and support easier learnability of the new setup. If changes were

such that the new system was too different, that would require the officers to support a

longer learning curve and make task performance more difficult.

Memory: To make location and retrieval quicker symbols and labels were provided. This

way, the officers would not need to look for items.

Flexibility: The new system was designed to enable easy location and retrieval of items

for officers at different experience levels.

The study was divided into three phases; the control phase, the improvement phase and

experimental phase. Following is a detailed description of the three phases:

Phase 1: Control Phase-Testing Participants on the existing arrangement of the storage

rooms-Testing Scenario

The officers were run through a familiar testing scenario. They were asked to retrieve equipment

pertaining to the testing scenario; “New hire scenario”. This scenario was selected as it was a very

common scenario faced by the Story County Sheriff’s Office, owing to the large number of new

hires being added to the team on a regular basis. Besides, it was a relatively easy scenario to test

the hypothesis of the study in a clear and unambiguous way.

Testing scenario-New Hire: A scenario where the officers were tasked with giving a newly hired

18

officer essential equipment required for them to begin their duty. This scenario mimics a real-life

scenario where a new hire is given equipment like uniforms etc. that is essential for them to be

considered officers on duty. They were provided the same list of items that they would use to

locate and retrieve equipment in a real scenario. The participants’ actions were monitored on video

for the time associated with the completion of the particular scenario assigned.

Phase 2: Improvement Phase-Updating the Storage Rooms

This phase involved:

Gathering all the responses provided by the officers in the post study questionnaires

Using the responses and the user-centered heuristics to develop an optimal room design

model using SIMIO, a simulation software capable of supporting the optimization of

resources and layouts of complex systems and scheduling processes: The user-centered

heuristics along with the responses provided by officers in the post-study questionnaire

were used while developing the model of the storage room using the SIMIO software; i.e.,

items were rearranged in the model in such a way that all of the equipment were visible at

all times, the room’s design was consistent with certain elements of the old design,

specifically those called out in the questionnaires (officers called out elements that they

liked about the existing system in the questionnaires) , the design did not require officers

to memorize the location of items and the new system could easily be navigated through

by experienced and inexperienced officers alike. This was followed by creating various

designs for the model using SIMIO (Version 10.174.16986). All storage shelves,

cupboards or any stand that hold items to be retrieved at some point were modeled as

‘Servers’ as are the obstructions that the existing storage space setup provides to the

19

participants. One ‘Source’ and one ‘Sink’ were provided to serve as a point from where

participants enter and exit the room, respectively. The model is explained it greater detail

with images below.

By conducting simulations on various design iterations, an optimal design was selected

such that it was in line with the user-centered heuristics and comments and such that it

would minimize the time taken to follow the path pertaining to the new hire scenario,

created using a list of items used by the Story County Sheriff’s Office for the new hire

equipment retrieval scenario.

Reorganizing the storage room based on the most optimal design obtained from SIMIO:

All the items were pulled out from the room and put back into the shelves once the room

was reorganized. The items were organized into specific shelves on the basis of most used

items, items used together in situations and items whose locations would not be changed

based on recommendations by officers in the questionnaires

SIMIO Model

All the servers represent shelves/obstacles. In the model of the existing system Servers 1-10

represent shelves while the other represent obstacles that hindered the officers’ ability to retrieve

items. The different paths represent the specific path followed by officers as they go into the

room to retrieve equipment pertaining to the scenario at hand; new hire. The simulation was run

using an arrival rate of one per min, for a period of 24 hours. The various paths indicated

represent the specific path that the officers were constrained by means of a list of equipment to

follow to retrieve the equipment pertaining to the scenario at hand; in this case the scenario of

giving a new hire all the equipment required for their first day. The time taken along each path

20

was recorded by SIMIO. Adding the times associated with following the paths indicated that the

amount of time taken to move from one point to the other in the existing system was twice that

of the time taken in the new system. For instance, moving from the source to server 1 required

the officers to go through server 13 in case of the existing system while moving the same

distance allowed officers to go direct to server 1. In such cases, the time taken was found to be

the sum of the times taken along each path. This simulation provided an idea of the potential

time wastage associated with the existing system and a need to redesign it to remove all the

obstacles that seemed to get in the way of the officers’ ability to accomplish the task at hand.

Therefore considering the above attributes as well as the time taken, the new system was

designed to keep certain elements of the existing system like the location of uniforms and

grooming equipment as per participant surveys collected after the first experiment. In all, the

time recorded, participant surveys and feedback, in addition to the human-centered attributes

were used to develop the model of the new system.

In this model, the retrieval process follows a fixed path depending on the scenario assigned

to the participant. The list of items to pick served as a means of providing for the path. The model

is developed according to the task. For example, if a particular task requires a participant to retrieve

items from shelf 2, 3, 5, 6 and then to exit the room, the model is developed in such a way that

paths are drawn from the source to server 2, server 2 to server 3, server 3 to server 5, server 5 to

server 6 and server 6 to the sink. The models were developed for the existing system and the total

time taken to retrieve an item and the number of items processed are obtained by running a

simulation of the model for 24 hours. Once this was done, an optimal process flow design was

developed in such a way that it resulted in the least amount of system time and greatest number of

processed items. Some human-centered concerns raised by the officers in the first questionnaire

21

like keeping the grooming section the same as before were also incorporated into the design.

Existing System

Figure 2: SIMIO model of the room before user-centered redesign

22

New System

Phase 3: Experimental Phase-Testing Participants on the updated storage rooms

This phase is more or less the same as Phase 1 with the only exception being that the experiment

was carried out on the new and updated process and then with labels and RFID cards on the

Figure 3: SIMIO model of the room after user-centered redesign

23

shelves. The participants were asked to fill a post-study questionnaire at the end of this phase. The

same new hire scenario was employed.

Figure 4: Storage room before user-centered redesign

24

Figure 5: Storage room after user-centered redesign

25

Results

Hypothesis

Null hypothesis: The mean of the time wasted before the redesign/reorganization equals

that after the reorganization

o µ𝑇_𝑏𝑒𝑓𝑜𝑟𝑒

= µ𝑇_𝑎𝑓𝑡𝑒𝑟

Alternate hypothesis: Time wasted between finds before the new design is greater than

the Time wasted between finds after the new design:

o µ𝑇_𝑏𝑒𝑓𝑜𝑟𝑒

> µ𝑇_𝑎𝑓𝑡𝑒𝑟

Significance value selected: α=0.05

Quantitative

Table 1: Summary of Quantitative Data

Dependent variable Before Change After Change

Average time spent to complete

the task

6.34 min 4.51 min

Time wasted on locating

equipment

3.05 min 0.78 min

Estimated cost associated with

the wasted time per officer

$2699.62 $693.34

Cost calculation: Percentage of time wasted x 8 hours a day x 5 days a week x 4 weeks x 12 months

x $27.66/hr. (approximate salary of deputy based on the Des Moines Register (2019)).

26

Table 2: Analysis of Variance

27

Table 3: Paired t-test

The data collected indicated a 74% reduction in the time wasted in between finds. Subsequently,

there was a 63% drop in the cost associated with this wasted time as a result of the user-centered

intervention. An ANOVA performed revealed a p-value of 0.00038. This indicates that the null

hypothesis can be rejected and a paired t-test performed on these times indicated a p-value of

0.0005 one-tailed (very much less than the significance value of 0.05) indicating that there is a

great possibility that there is a statistically significant difference between the time wasted in the

older system compared to that of the new system.

28

Qualitative

Figure 6: Response collected from post-study questionnaire after the experimental phase

The graph depicts the opinions of the officers with regard to certain heuristics obtained from the

post-study questionnaire. It indicates that most of the officers found the system organized, easy to

use and issue-free. They even expressed that such interventions would greatly help with other

operations at the Sheriff’s office

0% 10% 20% 30% 40% 50% 60% 70% 80% 90%

Organized

Ease of use

Likelihood to recommend such interventionsfor various operations at the Story County…

No issues with the exisiting system

PERCENTAGE OF PARTICIPANTS

SUR

VEY

QU

ESTI

ON

S

Organized Ease of use

Likelihood torecommend suchinterventions for

various operations atthe Story County

Sheriff's Office andbeyond

No issues with theexisiting system

Percentage of Participants 83% 67% 67% 50%

Qualitative Data

29

Discussion

The results suggest that the re-organization of the storage room reduced the amount of time spent

on looking for items, identifying them and navigating around items on the floor was reduced by

29%. The reason for the almost similar amount of time to complete the task can be owed to the

lack of familiarity of the new system. The significantly lower amount of wasted time as evidenced

by the ANOVA and paired t-test performed on the time wasted before and after the changes that

indicated p-values of 0.00038 and 0.0005 respectively suggests that the two times are significantly

different with the time wasted before the change being significantly larger than that of the time

wasted after the redesign

Additionally, a 63% reduction in the cost associated with the wasted time was observed.

The new design reduced the amount of time wasted in between finds significantly. This suggests

that the Sheriff’s office could spend the money saved by the new system for purposes that would

help it serve the community better. Both the quantitative and qualitative data obtained suggested

that the design of the system greatly supported the mental model of the participants. This was an

important consideration during the redesign of the room that enabled easier learnability to support

new and experienced officers alike and reduced confusion associated with the new system to an

extent (Rouse, W.B et al., 1992).

Almost all of the officers who participated in the experiment reported to have found the

system to be organized and intuitive to use. Many of them recommended the expansion of this area

we call “organizational engineering” to other operations within the Story County Sheriff’s Office

as well as those in other high-priority work settings. Above all, the data obtained indicated a strong

relation between human-centered design approaches and workplace design.

Unlike whatever was done earlier in literature (Karwowski, W et al. 1998), this study

provided a direct link between human-centered principles and organization of workplaces. No

30

variables but the design of the room was changed during the study.

31

Conclusion

Since the participant surveys indicated that the new system was easy to navigate and that it could

be used even by officers who are new, this study serves as a baseline study for more research in

this new area of “organization engineering”.

Future work could involve performing such interventions in different storage and inventory spaces

and can serve as a means of developing a model for developing a cost-benefit model that could

justify such interventions.

32

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CHAPTER 3. General Conclusion

The quantitative data obtained indicated that the newly organized storage room reduced the amount

of time wasted in between finds significantly, as evidenced by the ANOVA and paired t-test of the

wasted time before and after the change that revealed p-values of 0.00038 and 0.0005 respectively

for a significance value of 0.05. The cost associated with this wasted time was seen to have reduced

by 63%. This suggests that adopting the new design would allow the Sheriff’s officer to use the

money that was once spent on the wasted time in the old system to purchase equipment that could

aid the Sheriff’s office in accomplishing its tasks and serving the community.

The qualitative data obtained indicated that the new system was more intuitive and easier to

navigate through. The surveys indicated that most of the officers found the system more organized,

easier to learn and consistent with certain elements of the older system that were preferred by the

officers. Making the system consistent was seen as a means of supporting the mental model that

the officers already had about the room and the location of various equipment. As a result, the

officers did not spend a lot of time learning the new system. Thus, the organized rearrangement of

the room, the labels and symbols provided on shelves and cupboards and the consistent design

complete with careful mapping of the shelves to afford retrieval of the right items were seen to

made the location and retrieval process easy and more intuitive.

The cost associated with the wasted tine was calculated over the whole work day to indicate that

operations such as the location and retrieval of items could lead to a waste of time if it is not made

as efficient as possible. This would potentially rob the Sheriff’s office of precious time that could

be used on more important tasks such as solving crimes and serving the community. As a result,

39

the data this obtained indicates that the area of “organizational engineering” needs to be expanded

and applied to other such operations in time-critical settings like law enforcement to allow the

agency to spend more time on matters requiring greater attention.

The results of the experiments indicate that using user inputs and user-centered heuristics to

redesign a workplace setting is very effective in improving the productivity of the operation.

Design the system around the user takes into account the capabilities and limitations of the humans

using the system and as such helps the human to perform the tasks associated to the best of their

capabilities and in turn improves productivity. The future work should focus on expanding this

field to other time critical scenarios with law enforcement and beyond. Additionally, human-

centered models can be created that can justify costs and benefits associated with the

implementation of such interventions that can expand the adaptation of human-centered

approaches to a variety of industry types.

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APPENDIX A. Informed Consent Form

41

42

43

APPENDIX B. Pre-Study Questionnaire

44

APPENDIX C. Post-Study Questionnaire